The Rise and Fall of Ancient India’s Iron and Steel Metallurgy
Pradip reviews two new books on the history and products of ancient Indian iron and steel technology.
Infinity Foundation Series – Contributions to History of Indian Science and Technology Rupa and Co.
• Marvels of Indian Iron through the Ages by R. Balasubramanian (2008)
• History of Iron Technology in India – From Beginning to Premodern Times by Vibha Tripathi (2008)
It is a well acknowledged fact that the level of societal development is closely linked to the development of iron and steel industry. It is no wonder therefore that the world production of steel today is around 1.4 billion tons per year, also emphasizing the importance of this technology to us in India. The production of iron ore (iron oxide), the basic natural raw material required to produce steel is more than two billions tons per year. Today, India is the fourth largest producer of iron ore (after China, Brazil, Australia) and the third largest consumer of steel (but consuming only 60 million tons of steel as compared to China which is consuming close to 500 million tons with a comparable population).
India is exporting around 50% of its iron ore production currently.
Despite India being a large producer and consumer of steel, it is not considered the source of new technologies today. It is therefore important to note that this was not case until the advent of British East India Company. Two books published recently on the iron and steel technology in ancient India up to Pre-British times are an important contribution to documenting the rise and decline of this technology in India. While the modern iron and steel technology was patented and commercialized in Europe in the mid-nineteenth century, our Indian craftsmen, more than two thousand years back, had mastered this technology of making excellent iron and steel. It is this fascinating saga of world class technological products being manufactured and exported to other parts of the world which is captured in the two recent volumes published as a part of the Infinity Foundation Series.
History of Iron Technology in India (From Beginning to Pre-modern Times), authored by Vibha Tripathi, an eminent historian from Banaras Hindu University, covers the long span of Indian history stretching over three and a half millennia from the first half of the second millennium BCE to pre-modern times. It traces the development of iron technology from the humble beginning when Indian artisans melting relatively low temperature metals like copper, copper – zinc (brass) and copper – tin (bronze). They hit upon the process of producing iron and also evolved it into an advanced technology and a flourishing industry, thereby becoming a supplier of the best iron and steel, on a tonnage scale, to all parts of the world.
With a systematic review of the recorded evidence, Vibha Tripathi demolishes the myth that iron reached India through diffusion from the West as late as the sixth-fifth century BCE. She argues that there was an independent origin and development of iron ore mining, extraction and manufacturing technology rooted in the raw materials available in India. Well recognized occurrence of iron is reported around 1500 to 1000 BCE in all parts of India.
Tripathi refers to Arthashastra, a treatise on statecraft composed in the 4th-3rd century BCE, authored by Chanakya during Mauryan times. It mentions iron as “Kalyasa”. There is even a discussion of mines as an important source of income for the Mauryan state. It mentions the post of superintendent of mines to supervise and manage the mines. It lays down the duties of the director of mines in detail.
In the sixth-fifth century BCE, Sushruta began surgery using surgical tools made of iron requiring precision and quality of the highest order. Varahamitra in his “khadga lakshanam” dated 550 AD, elaborated on the carburization and hardening processes of iron swords. Classification of different kinds of irons is included in the famous Ras Ratna Samuchhaya, a tenth-twelfth century text on alchemy. For example, Kanta Loha, Tikshna Loha and Munda having distinct properties are well documented in the text.
Iron production was sufficiently developed in India by the 4th-5th century CE. There was a flourishing trade between India and Iran, Iraq (Mesopotamia), Indonesia, China and Africa. There are references to rich Indian traders living in Mesopotamia. India received gold in return for export of copper, tin, lead and solid steel ingots, spices, drugs, cotton cloth, leather goods, precious stones and timber. The Indian metallurgical industry was one of the most advanced industries in the world at that time, according to Vibha Tripathi.
Iron technology reached new heights of excellence during the Gupta period (3rd-to-6th centuries CE). Massive iron based artifacts such as the Delhi iron pillar testify to the level of metallurgical skills mastered by Indians. The processes such as rapid cooling, carbon alloying, quenching, tempering, hardening and forge welding were known to them. Large lead baths were being used to achieve uniform heating of a bundle of wrought iron bars to the forging temperature.
India is endowed with rich iron ore deposits and hence iron ore mining was being carried out in different parts of India for more than two thousand years. According to Dharmapal there were several important centres of iron ore mining, smelting and manufacture spread over from Kumaon-Garwhal to Assam, Hyderabad, Karnataka, Orissa, Bengal, Tamil Nadu and Madhya Pradesh. Vibha Tripathi has referred to the documented evidence about the flourishing iron and steel industry in the late nineteenth and early twentieth century. Wages for workers were paid in kind. For example ordinary workers received 2-3% of the produce. The persons in charge of smelting house and forging house on the other hand received six and eight percent of the produce respectively.
Professor Balasubramaniam (Bala), a well known metallurgist from IIT Kanpur, in his book Marvels of Indian Iron Through the Ages, has documented the marvelous creations of the Indian craftsmen, the massive iron pillars, beams and cannons produced in different parts of India by forge welding the lumps of heated iron. The most famous example of the status of Indian technological excellence in the past is the magnificent Delhi iron pillar weighing seven tons, which remains an object of technological curiosity even today.
The fact that these massive iron objects have not corroded even after more than two thousand years has also been explained in terms of contemporary scientific understanding by Bala in this book. Furthermore, the book also contains a section on the world renowned Wootz steel technology invented by Indians.
Forge-welded and non-corroding iron pillars and beams
As illustrated by Bala in the book, Indian artisans in the early days had not found a way to attain
a temperature of 1540 degrees centigrade (the temperature at which iron melts) and hence they could not cast iron (as they had done for copper, brass and bronze, for example by the famous lost wax process invented in India). Hence they practiced forge welding. The lumps of iron (containing traces of slag) were heated and fused together by a process known as forge welding.
This process to produce iron objects of a large diameter and weighing several tons is very well illustrated by Bala in the book. Documentary evidence is provided to substantiate the way these pillars, beams and cannons were manufactured and transported.
The famous iron pillar in Delhi was set up by the iron smiths in India in the Gupta period in a place called Udaygiri near Vidisha and Sanchi around 400 CE. It was later moved to Delhi by Iltumish in 1233 CE. The excellent corrosion resistance of iron pillar is attributed to the presence of phosphorous (using high phosphorous containing iron ores) in the reduced iron. Similar technology was used to produce an even longer pillar (13 meters) lying in three broken pieces in front of the Lal Masjid in Dhar, situated near Indore in Madhya Pradesh. Dhar was the capital of Malwa founded by King Bhoja (1010 - 1053 CE). Archaeological study indicates that the Dhar pillar was also erected during the Gupta period.
Another famous iron pillar at the Mookambika temple in Kodachari hill, located in a town near Mangalore, also belongs to the same era. The iron beams lying in the Surya temple at Konark are of even larger dimensions. These iron beams were used to support the roof stones of the famous temples at Bhubaneswar as well as Puri. In fact non-corroding iron beams were being used extensively in building temples in Orissa dating back to the sixth and thirteenth centuries CE.
Forge-welded iron cannons of India
According to Bala, the forgewelded cannons truly represent the mastery of iron ore mining, extraction and manufacturing technology of Indian blacksmiths. As opposed to cast iron cannon technology developed in Europe, Indians practiced forge welding technology and produced large cannons from direct-reduced wrought iron. Bala has described in detail the technology as well as the history of some of the most massive forge-welded iron cannons in the world which are scattered all over the Indian subcontinent – Thanjavur, Dhaka, Murshidabad, Bishnupur, Jhansi, Assam, Tripura, Gulbarga, Bijapur, Bidar, Golconda, Hyderabad, and many Deccan forts. The cannon technology was a crucial element in the rise and fall of several dynasties in India such as Mughals, Marathas, Sikhs and Rajputs. It is certain that the latest technologies prevalent in Europe were also known to Indians.
For example when the British defeated Tipu Sultan in 1799, they were astonished by the quality of his cannon. Nine hundred and twenty seven cannon were captured after the fall of Srirangapatnam in 1799. European colonizers used superior cast iron cannons and also systematically destroyed the forge-welded cannons from the Indian forts, according to Bala.
The above-mentioned examples illustrate the level of technological maturity achieved by Indian artisans and suggest the existence of a flourishing industry capable of producing iron and steel in hundreds of tons. It may be interesting to note that the British rated Indian iron highly and used it in preference to the iron produced by their own industry in making the famous “tubular bridge” in early nineteenth century across the Menai Straits in UK. It has also been recorded that 50 tons of Indian steel were used in the construction of the famous London Bridge in UK.
One of the greatest technological achievements to originate from the Indian subcontinent is Deccan Wootz Steel, often referred to as “the wonder material of the orient”. The world famous Damascus swords were made of Wootz steel and these were considered to be the most prized possessions and gift items (certainly more precious than gold and silver) by the aristocracy. There is no evidence to show that any of the nations of antiquity besides the Indians were acquainted with the art of making steel. The word Wootz is a distortion of the Kannada-Telugu word Ukku, for steel.
Quintus Curtis records for example that a present of steel cakes was made to Alexander of Macedonia by Porus after his defeat in 326 BCE. Sir Robert Hadfield, a metallurgist, has reported on the possibility of the use of the chisels made of Indian steel and Indian craftsmen in the construction of the massive Egyptian pyramids.
Wootz steel is an iron carbon alloy containing 1 to 1.8% carbon produced by the crucible melting process invented in India. The basic process, even though not fully understood, consisted of heating direct reduced iron with other ingredients including charcoal contained in a closed clay crucible. The crucibles containing steel were carefully cooled so that the metal solidified at the bottom of the crucible. The Wootz steel cake was of high quality. That the cooling of the crucible was crucial was well known to Indian metallurgists of that era since different ways of cooling in the furnace itself, in dry sand heaps, in moist clay, or by quenching with water are all well documented. Carburization of iron to controlled levels of carbon is thus the key to manufacturing Wootz steel. This technology was mastered by Indians quite early in the history of civilization, as early as 810 BCE. Studies indicate that the crucibles excavated in Tamilnadu date back to 250 BCE.
The blades made of Wootz steel showed an intricate wavy pattern on the surface. A judicious combination of high strength and excellent formability in steels to be able to make sharp blades remains a technological challenge to this day. In fact the rigorous research conducted to understand and master the Wootz steel technology in Europe laid the foundations of modern metallurgy.
Decline of Indian iron and steel industry in Pre-British era
Both Vibha Tripathi and Balasubramaniam also discuss the possible reasons of the decline of the iron and steel industry in India. Tripathi has a separate section in her book where she brings out the possible reasons of the decline and death of the indigenous iron and steel industry in India with the advent of the British colonialists. It is interesting that the steel plants which were commissioned in the late nineteenth and early twentieth century in India were based on imported European technology and had no connection with traditional Indian technology perfected over centuries.
According to Vibha Tripathi “With industrialization and imperial designs of foreign rule a decline set in…….. The iron industry could not withstand the onslaught of the colonial forces working against its interests in a planned way. Once the blast furnaces came into existence in Britain, production started at a much cheaper rate…It could hardly compete with the cheap British pig iron being imported. …. The laws enforcing non-felling of trees in the forest deprived the charcoal based indigenous iron industry of its very basic raw material. It made production of iron impossible. The powerful lobby in Britain succeeded.” The colonizers succeeded in enslaving the Indian sub-continent in every sense of the word by systematically destroying the manufacturing capacity of India.
Both the authors also ascribe the decline to the reluctance of master craftsmen to document the technological secrets and to share the knowledge with others except with their favored apprentices. Hence some of the technologies could not be developed further and declined with the decline of the fortunes of the select group of families who knew the process secrets.
Tripathi and Bala passionately plead for supporting research into and revival of the ancient Indian method of making high strength, non-corroding, crucible steel and converting them to sharp cutting objects requiring high levels of formability. It is hoped that research on these topics by Indian professionals will unravel not only the technological mysteries of steel making but also the socio-economic and political circumstances which led to the decline of the Indian manufacturing industry. This analysis of the historical facts may also equip us to compete today in a world facing challenges of technology denial by big powers to those who need it.
Both the books have high production values with good visuals, and the series editor Dr D P Agrawal, Infinity Foundation and Rupa Books need to be complimented for providing such valuable books on the history of Indian science and technology.
Dr Pradip is a well known Metallurgist and Material Scientist and a Fellow of Indian National Academy of Engineering, Pune